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setuid(geteuid());? 831+ messages / 4 participants [nested] [flat]
* setuid(geteuid());? @ 2001-04-21 15:04 Peter Eisentraut <[email protected]> 0 siblings, 1 reply; 831+ messages in thread From: Peter Eisentraut @ 2001-04-21 15:04 UTC (permalink / raw) To: pgsql-hackers This call setuid(geteuid()); is found in backend/utils/init/postinit.c. AFAICT, this does nothing. Anyone got an idea? -- Peter Eisentraut [email protected] http://funkturm.homeip.net/~peter ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 15:07 Bruce Momjian <[email protected]> parent: Peter Eisentraut <[email protected]> 0 siblings, 1 reply; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 15:07 UTC (permalink / raw) To: Peter Eisentraut <[email protected]>; +Cc: pgsql-hackers > This call > > setuid(geteuid()); > > is found in backend/utils/init/postinit.c. AFAICT, this does nothing. > Anyone got an idea? Well, from my BSD manual it says: The setuid() function sets the real and effective user IDs and the saved set-user-ID of the current process to the specified value. The setuid() so it seems to make sure the real/saved uid matches the effective uid. Now, considering we don't use uid/euid distinction for anything, I agree it is useless and should be removed. I don't see any mention of getuid() except in odbc and pg_id. Seems they should be geteuid() too. -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 16:29 Tom Lane <[email protected]> parent: Bruce Momjian <[email protected]> 0 siblings, 3 replies; 831+ messages in thread From: Tom Lane @ 2001-04-21 16:29 UTC (permalink / raw) To: Bruce Momjian <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers Bruce Momjian <[email protected]> writes: > so it seems to make sure the real/saved uid matches the effective uid. > Now, considering we don't use uid/euid distinction for anything, I agree > it is useless and should be removed. No, it is NOT useless and must NOT be removed. The point of this little machination is to be dead certain that we have given up root rights if executed as setuid postgres. The scenario we're concerned about is where real uid = root and effective uid = postgres. We want real uid to become postgres as well --- otherwise our test to prevent execution as root is a waste of time, because nefarious code could become root again just by doing setuid. See the setuid man page: if real uid is root then setuid(root) will succeed. regards, tom lane ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 16:43 Tom Lane <[email protected]> parent: Tom Lane <[email protected]> 2 siblings, 0 replies; 831+ messages in thread From: Tom Lane @ 2001-04-21 16:43 UTC (permalink / raw) To: Bruce Momjian <[email protected]>; Peter Eisentraut <[email protected]>; pgsql-hackers >> so it seems to make sure the real/saved uid matches the effective uid. >> Now, considering we don't use uid/euid distinction for anything, I agree >> it is useless and should be removed. > No, it is NOT useless and must NOT be removed. But it would make sense to move it over to main.c where the primary test for not running as root is, since these are closely related considerations: we don't want either euid or ruid to be root. I'll make that change unless I hear objections... regards, tom lane ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 16:51 Bruce Momjian <[email protected]> parent: Tom Lane <[email protected]> 2 siblings, 1 reply; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 16:51 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers > Bruce Momjian <[email protected]> writes: > > so it seems to make sure the real/saved uid matches the effective uid. > > Now, considering we don't use uid/euid distinction for anything, I agree > > it is useless and should be removed. > > No, it is NOT useless and must NOT be removed. The point of this little > machination is to be dead certain that we have given up root rights if > executed as setuid postgres. The scenario we're concerned about is > where real uid = root and effective uid = postgres. We want real uid > to become postgres as well --- otherwise our test to prevent execution > as root is a waste of time, because nefarious code could become root > again just by doing setuid. See the setuid man page: if real uid is > root then setuid(root) will succeed. I understand, but how do we get suid execution. Does someone have to set the seuid bit on the executable? -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 16:58 Tom Lane <[email protected]> parent: Bruce Momjian <[email protected]> 0 siblings, 1 reply; 831+ messages in thread From: Tom Lane @ 2001-04-21 16:58 UTC (permalink / raw) To: Bruce Momjian <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers Bruce Momjian <[email protected]> writes: > I understand, but how do we get suid execution. Does someone have to > set the seuid bit on the executable? Probably so, but I could see someone thinking they could do that as a substitute for saying "su - postgres" on every startup. If we are going to take the trouble to refuse to run when euid = 0, then it also behooves us to guard against ruid = 0. regards, tom lane ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 17:08 Bruce Momjian <[email protected]> parent: Tom Lane <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 17:08 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers > Bruce Momjian <[email protected]> writes: > > I understand, but how do we get suid execution. Does someone have to > > set the seuid bit on the executable? > > Probably so, but I could see someone thinking they could do that as a > substitute for saying "su - postgres" on every startup. > > If we are going to take the trouble to refuse to run when euid = 0, > then it also behooves us to guard against ruid = 0. OK, that's what I thought. The command is not needed in our default configuration. I agree we should prevent people from setting up bad configurations if we can. -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 17:17 Peter Eisentraut <[email protected]> parent: Tom Lane <[email protected]> 2 siblings, 2 replies; 831+ messages in thread From: Peter Eisentraut @ 2001-04-21 17:17 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Bruce Momjian <[email protected]>; pgsql-hackers Tom Lane writes: > Bruce Momjian <[email protected]> writes: > > so it seems to make sure the real/saved uid matches the effective uid. > > Now, considering we don't use uid/euid distinction for anything, I agree > > it is useless and should be removed. > > No, it is NOT useless and must NOT be removed. The point of this little > machination is to be dead certain that we have given up root rights if > executed as setuid postgres. The scenario we're concerned about is > where real uid = root and effective uid = postgres. If effective uid = postgres, then this will execute setuid(postgres), which does nothing. > We want real uid > to become postgres as well --- otherwise our test to prevent execution > as root is a waste of time, because nefarious code could become root > again just by doing setuid. See the setuid man page: if real uid is > root then setuid(root) will succeed. That is a valid concern, but the code doesn't actually prevent this. I just tried chmod u+s postgres su - postmaster -D ... Then loaded the function #include <postgres.h> int32 touch(int32 a) { if (setuid(0) == -1) elog(ERROR, "setuid: %m"); elog(DEBUG, "getuid = %d, geteuid = %d", getuid(), geteuid()); system("touch /tmp/foofile"); setuid(500); /* my own */ return a + 1; } and the output was DEBUG: getuid = 0, geteuid = 0 and I got a file /tmp/foofile owned by root. ISTM that the best way to prevent this exploit would be to check for both geteuid() == 0 and getuid() == 0 in main.c. -- Peter Eisentraut [email protected] http://funkturm.homeip.net/~peter ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 17:29 Tom Lane <[email protected]> parent: Peter Eisentraut <[email protected]> 1 sibling, 2 replies; 831+ messages in thread From: Tom Lane @ 2001-04-21 17:29 UTC (permalink / raw) To: Peter Eisentraut <[email protected]>; +Cc: Bruce Momjian <[email protected]>; pgsql-hackers Peter Eisentraut <[email protected]> writes: >> We want real uid >> to become postgres as well --- otherwise our test to prevent execution >> as root is a waste of time, because nefarious code could become root >> again just by doing setuid. See the setuid man page: if real uid is >> root then setuid(root) will succeed. > That is a valid concern, but the code doesn't actually prevent this. After reading the setuid man page a third time, I think you are right. On machines that have setreuid(), or even better setresuid(), we could force the ruid (and suid for good measure) to match euid. Otherwise we probably should refuse to start unless getuid matches geteuid. Hmm ... setresuid may be an HP-ism ... does anyone else have that? setreuid appears to be a BSD-ism, so it ought to be reasonably popular. regards, tom lane ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 17:47 Tom Lane <[email protected]> parent: Tom Lane <[email protected]> 1 sibling, 2 replies; 831+ messages in thread From: Tom Lane @ 2001-04-21 17:47 UTC (permalink / raw) To: Peter Eisentraut <[email protected]>; Bruce Momjian <[email protected]>; pgsql-hackers I said: > On machines that have setreuid(), or even better setresuid(), we could > force the ruid (and suid for good measure) to match euid. Otherwise we > probably should refuse to start unless getuid matches geteuid. But on third thought, it's not worth the trouble of adding two more configure tests to support a configuration that I doubt anyone uses anyway (ie, setuid postgres executable). Let's just remove the setuid() and add a check for getuid() == geteuid() in main.c. Peter, unless you've already started in on this, I can take care of it --- I see a couple of other nits I want to fix in those two files, too. regards, tom lane ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 18:13 Peter Eisentraut <[email protected]> parent: Tom Lane <[email protected]> 1 sibling, 0 replies; 831+ messages in thread From: Peter Eisentraut @ 2001-04-21 18:13 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Bruce Momjian <[email protected]>; pgsql-hackers Tom Lane writes: > I said: > > On machines that have setreuid(), or even better setresuid(), we could > > force the ruid (and suid for good measure) to match euid. Otherwise we > > probably should refuse to start unless getuid matches geteuid. > > But on third thought, it's not worth the trouble of adding two more > configure tests to support a configuration that I doubt anyone uses > anyway (ie, setuid postgres executable). Let's just remove the setuid() > and add a check for getuid() == geteuid() in main.c. > > Peter, unless you've already started in on this, I can take care of it > --- I see a couple of other nits I want to fix in those two files, too. Please do. I just ran across it for the session authorization deal, which would be easy to merge. -- Peter Eisentraut [email protected] http://funkturm.homeip.net/~peter ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 19:57 Bruce Momjian <[email protected]> parent: Tom Lane <[email protected]> 1 sibling, 0 replies; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 19:57 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers > > That is a valid concern, but the code doesn't actually prevent this. > > After reading the setuid man page a third time, I think you are right. > > On machines that have setreuid(), or even better setresuid(), we could > force the ruid (and suid for good measure) to match euid. Otherwise we > probably should refuse to start unless getuid matches geteuid. > > Hmm ... setresuid may be an HP-ism ... does anyone else have that? > setreuid appears to be a BSD-ism, so it ought to be reasonably popular. I have setreuid on BSD/OS, no setresuid. -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 19:58 Bruce Momjian <[email protected]> parent: Tom Lane <[email protected]> 1 sibling, 0 replies; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 19:58 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; pgsql-hackers > I said: > > On machines that have setreuid(), or even better setresuid(), we could > > force the ruid (and suid for good measure) to match euid. Otherwise we > > probably should refuse to start unless getuid matches geteuid. > > But on third thought, it's not worth the trouble of adding two more > configure tests to support a configuration that I doubt anyone uses > anyway (ie, setuid postgres executable). Let's just remove the setuid() > and add a check for getuid() == geteuid() in main.c. > > Peter, unless you've already started in on this, I can take care of it > --- I see a couple of other nits I want to fix in those two files, too. Good. That function call clearly needs a comment added. -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 20:03 Bruce Momjian <[email protected]> parent: Peter Eisentraut <[email protected]> 1 sibling, 1 reply; 831+ messages in thread From: Bruce Momjian @ 2001-04-21 20:03 UTC (permalink / raw) To: Peter Eisentraut <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-hackers > Tom Lane writes: > > > Bruce Momjian <[email protected]> writes: > > > so it seems to make sure the real/saved uid matches the effective uid. > > > Now, considering we don't use uid/euid distinction for anything, I agree > > > it is useless and should be removed. > > > > No, it is NOT useless and must NOT be removed. The point of this little > > machination is to be dead certain that we have given up root rights if > > executed as setuid postgres. The scenario we're concerned about is > > where real uid = root and effective uid = postgres. > > If effective uid = postgres, then this will execute setuid(postgres), > which does nothing. I am a little confused. BSD/OS manual page says: The setuid() function sets the real and effective user IDs and the saved set-user-ID of the current process to the specified value. The setuid() function is permitted if the specified ID is equal to the real user ID of the process, or if the effective user ID is that of the super user. ... If the user is not the super user, or the uid specified is not the real, effective ID, or saved ID, these functions return -1. so why does your test work? Does your manual say something different? If setuid() sets user/effective/saved to postgres, how can you get back root? -- Bruce Momjian | http://candle.pha.pa.us [email protected] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ^ permalink raw reply [nested|flat] 831+ messages in thread
* Re: setuid(geteuid());? @ 2001-04-21 20:43 Peter Eisentraut <[email protected]> parent: Bruce Momjian <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Peter Eisentraut @ 2001-04-21 20:43 UTC (permalink / raw) To: Bruce Momjian <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-hackers Bruce Momjian writes: > so why does your test work? Does your manual say something different? > If setuid() sets user/effective/saved to postgres, how can you get back > root? : setuid sets the effective user ID of the current process. If the : effective userid of the caller is root, the real and saved user ID's : are also set. : : Under Linux, setuid is implemented like the POSIX version with the : _POSIX_SAVED_IDS feature. This allows a setuid (other than root) : program to drop all of its user privileges, do some un-privileged : work, and then re-engage the original effective user ID in a secure : manner. I suppose your system doesn't have the _POSIX_SAVED_IDS feature. I also have: : CONFORMING TO : SVr4, SVID, POSIX.1. Not quite compatible with the 4.4BSD call, : which sets all of the real, saved, and effective user IDs. On your system you would have to use seteuid() to do what setuid() does here. One more reason to avoid this area when possible. -- Peter Eisentraut [email protected] http://funkturm.homeip.net/~peter ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 831+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 831+ messages in thread
end of thread, other threads:[~2025-07-15 10:45 UTC | newest] Thread overview: 831+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2001-04-21 15:04 setuid(geteuid());? Peter Eisentraut <[email protected]> 2001-04-21 15:07 ` Bruce Momjian <[email protected]> 2001-04-21 16:29 ` Tom Lane <[email protected]> 2001-04-21 16:43 ` Tom Lane <[email protected]> 2001-04-21 16:51 ` Bruce Momjian <[email protected]> 2001-04-21 16:58 ` Tom Lane <[email protected]> 2001-04-21 17:08 ` Bruce Momjian <[email protected]> 2001-04-21 17:17 ` Peter Eisentraut <[email protected]> 2001-04-21 17:29 ` Tom Lane <[email protected]> 2001-04-21 17:47 ` Tom Lane <[email protected]> 2001-04-21 18:13 ` Peter Eisentraut <[email protected]> 2001-04-21 19:58 ` Bruce Momjian <[email protected]> 2001-04-21 19:57 ` Bruce Momjian <[email protected]> 2001-04-21 20:03 ` Bruce Momjian <[email protected]> 2001-04-21 20:43 ` Peter Eisentraut <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]>
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